So says CNN:

The average human head weighs 10 pounds in a neutral position — when your ears are over your shoulders. For every inch you tilt your head forward, the pressure on your spine doubles. So if you're looking at a smartphone in your lap, your neck is holding up what feels like 20 or 30 pounds…. Staying in what experts call the "forward head posture" can lead to muscle strain, disc herniations and pinched nerves. Over time, it can even flatten or reverse the natural curve of your neck.

As your mother used to say: Be careful or it might stay like that.

Dr. Michelle Collie, director of Performance Physical Therapy in Rhode Island, says she started seeing patients with head, neck and back pain caused by mobile devices six or seven years ago. Recently she says Text Neck has increased dramatically, especially among her younger patients.